Umbilical cord blood (UCB) is being used increasingly as an alternative source of hematopoietic stem cells (HSCs) for related and unrelated allogeneic transplant in children and adults.[1, 2] The advantages of using HSCs from UCB are prompt availability, low risk of transmissible viral infection, low risk of graft-versus-host disease, no risk to the donors, more flexible human leukocyte antigen (HLA) matching criteria, absence of donor attrition, and better recruitment of ethnic minorities.3-7 The major limitation of the UCB is the fixed cell dose after collection and studies have demonstrated that transplant outcome is directly related to UCB cell dose.[8, 9]
The Tzu-Chi Cord Blood Bank (TCCBB), a public, not-for-profit, altruistic medical institution, was established in 2001 to provide an alternative source of HSCs for patients in need of transplant. UCB banking needs huge financial investment and efficient organized efforts. The cost of processing and storing each unit of UCB is high, which makes it an encumbrance for patients in need of UCB transplant. Therefore, improving the quality of UCB collection is important for enhancing not only the transplant outcome but also the operational efficiency of a UCB bank. Owing to a high rate of donation exclusion and discarded storage units at the beginning of collection, we began recording the exclusion reasons in 2004. In this study, we examined the reasons for the ineligible UCB donations in a 3-year period from 2004 to 2006 to improve the efficiency of UCB banking programs.
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- Materials and Methods
- Conflict of Interest
Overall, 10,685 potential donors consented to donate UCB to our facility: 1830, 3806, and 5049 in 2004, 2005, and 2006 (Table 1). During the whole study period, 6280 (58.8%) donations were ineligible and the exclusion rates in 2004, 2005, and 2006 were 93.1, 48.4, and 54.1%, respectively. We excluded 612 donations from pregnant women before delivery, 133 UCB units during delivery, 80 units before processing, 5010 units during processing, and 421 units after freezing. There were 24 UCB units with unknown reasons of ineligibility. The exclusion in all intended donations for each phase decreased gradually. The most common phases of exclusion were during processing (79.8% of all exclusions), before collection (9.7%), and after freezing (6.7%).
Table 1. 10,685 UCB donations to the TCCBB from 2004 to 2006*
|Total number of donors||1,830||3,806||5,049||10,685|
|Eligible UCB units||126 (6.9)||1,963 (51.6)||2,316 (45.9)||4,405 (41.2)|
|Exclusion||1,704 (93.1)||1,843 (48.4)||2,733 (54.1)||6,280 (58.8)|
|Phase 1: before collection||234 (12.8)||258 (6.8)||120 (2.4)||612 (5.7)|
|Phase 2: during delivery||90 (4.9)||37 (1.0)||6 (0.1)||133 (1.2)|
|Phase 3: before processing||14 (0.8)||55 (1.4)||11 (0.2)||80 (0.7)|
|Phase 4: during processing||1,232 (67.3)||1,319 (34.7)||2,459 (48.7)||5,010 (46.9)|
|Phase 5: after freezing||122 (6.7)||166 (4.4)||133 (2.6)||421 (3.9)|
|Unknown||12 (0.7)||8 (0.2)||4 (0.1)||24 (0.2)|
The number and proportion of reasons for exclusion before collection, during delivery, and during the processing are presented in Table 2. The association among the reasons of UCB exclusion and the time periods was significant (p < 0.001). Of the 612 donations excluded at the time before collection, 242 (39.5%) were discarded on the basis of maternal medical problems and most were because of maternal fever or sickness. In addition, 157 (25.7%) were ineligible on the basis of obstetric factors, whereas the most common reason was premature rupture of membrane more than 24 hours earlier; 124 (20.3%) were discarded because of the artificial errors, 53 (8.7%) due to holiday reason, and 36 (5.9%) by cancellation. The annual occurrence rates for each reason varied significantly, except for the maternal medical problems (Table 2). For example, the rate of discarded UCB units because of the artificial errors before collection decreased to 5.7% in 2006, which was lower than that in 2004 (26.1%). A similar pattern was observed for reasons including obstetric problems and cancellation.
Table 2. The number and reasons for discarded UCB before collection, during delivery, before processing, during processing, and after freezing*
|Reason||Number (%)||2004||2005||2006||p value|
|Phase 1: before collection||612||234||258||120|| |
|Maternal medical problem||242 (39.5)||73 (30.0)||93 (36.0)||76 (63.3)||0.236|
|Maternal obstetric problem||157 (25.7)||64 (27.4)||56 (21.7)||37 (30.8)||0.025|
|Artificial error||124 (20.3)||61 (26.1)||56 (21.7)||7 (5.8)||<0.001|
|Holiday||53 (8.7)||13 (5.6)||40 (15.5)||0 (0)||<0.001|
|Cancelation (consent withdrawn or obstetric decision)||36 (5.9)||23 (9.8)||13 (5.0)||0 (0)||<0.001|
|Phase 2: during delivery||133||90||37||6|| |
|Infant||115 (86.5)||81 (90)||32 (86.5)||2 (33.3)||<0.001|
|Placenta or umbilical cord||18 (13.5)||9 (10)||5 (13.5)||4 (66.7)||0.311|
|Phase 3: before processing||80||14||55||11|| |
|Transportation||63 (78.8)||7 (50)||50 (90.9)||6 (54.5)||<0.001|
|Artificial errors||17 (21.3)||7 (50)||5 (9.1)||5 (45.5)||0.78|
|Phase 4: during processing||5010||1232||1319||2459|| |
|Low weight||3053 (60.9)||881 (71.5)||986 (74.7)||1186 (48.2)||<0.001|
|Low cell count||1941 (38.7)||349 (28.3)||324 (24.6)||1268 (51.6)||<0.001|
|Clots||16 (0.3)||2 (0.2)||9 (0.7)||5 (0.2)||0.099|
|Phase 5: after freezing||421||122||166||133|| |
|Microbial contamination||260 (61.8)||61 (50)||96 (57.8)||103 (77.4)||0.003|
|Questionnaire for infant at 6 months of age||154 (36.6)||59 (48.4)||65 (39.2)||30 (22.6)||0.001|
|Positive ID marker||7 (1.7)||2 (1.6)||5 (3.0)||0 (0)||1|
At the time during delivery, the major reason for an ineligibility to donate was due to problems pertaining to the infants (86.5%) such as meconium stain and prematurity, whereas the other problems included those pertaining to the placenta and umbilical cord (13.5%). The rate of discarded UCB pertaining to the infant during delivery was lower in 2006 than that before 2006. At the time before processing, the exclusion was stable except for a high number in 2005. This increase resulted from bad weather (e.g., typhoon) in that year. The most common phase for deferral of UCB was at the time during processing. In particular, the most common reason was low weight (60.9%), followed by low cell count (38.7%). These two reasons were also the leading causes of exclusion in the overall cohort (48.6 and 30.9%, respectively). The exclusion rate due to the low unit weight decreased significantly in 2006 but the percentage of low cell count increased annually (p < 0.001).
We excluded 421 units at the time after freezing: 260 (61.8%) units because of microbial contamination, 154 (36.6%) units because of an unsuitable condition reported in the infants' 6-month follow-up questionnaire, and seven (1.7%) cases because of positive ID markers. Glucose-6-phosphate dehydrogenase deficiency comprised the majority (76.5%) of exclusion for baby problems noted at 6 month of age. Three UCB units were removed because of malignancy (acute leukemia, one; neuroblastoma, one; and pelvic mass, one), three because of hypothyroidism, two because of chromosome abnormality, two because of genitourinary anomalies, and two because of infant death. An additional 7 UCB units were discarded due to other diseases in infants including Gaucher disease, inborn error, histiocytosis syndrome, cleft palate with spina bifida, extremity anomalies, biliary atresia, and jaundice. The percentage of exclusions because of problems noted in the questionnaire on infant health status at 6 months of age significantly decreased through the years. Although the microbial contamination rate increased in the phase after freezing it decreased from 3.3% in 2004 to 2.0% in 2006 in all the collected UCB units. Forty-nine UCB units were excluded because information on the infants' 6-month follow-up was unavailable, and 24 units were excluded due to maternal familial health problems. Lack of questionnaire submission on infant health status at 6 months of age decreased from 13.1 and 15.6% of the frozen UCB in 2004 and 2005, respectively, to 5.2% in 2006.
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- Materials and Methods
- Conflict of Interest
UCB banking is a multidisciplinary program involving hematologists, obstetricians, nurses, technologists, transfusionists, administrative staff, and other professionals. The estimated cost of UCB collection, processing, and cryopreservation is approximately US$11,602 to US$15,061 per unit. UCB banks usually retrieve their expenses by charging transplant institutions for each unit released. The expenditure is high for patients needing cord blood transplants. Therefore, it is important to optimize recruitment, processing, and storage to decrease the cost of each UCB unit especially for public UCB banks. Several studies have shown different exclusion reasons of UCB units but most of these studies did not provide an analysis from recruitment throughout storage and follow-up. We have provided a comprehensive analysis of the reasons for exclusion in a consecutive 3-year period of our UCB banking experience to help future management of UCB banking.
During the 3-year study period, 4405 of 10,685 UCB units (41.2%) were cryopreserved in our cord blood bank with a mean of 3561 donations per year or 68 donations per week. This was a very large number of donations in comparison to those reported in previous literature.13-16 During this study period, the exclusion rate decreased, while donations rapidly and steadily increased. We did not design any strategy to improve the collection but kept recording the reasons for exclusion and providing training for our administrative staff and volunteers. The exclusion in all intended donations for each phase decreased gradually except for Phase 4 (Table 1). This reflects that it is possible to reduce the exclusion rate. The only nonmodifiable factor is the UCB cell count. However, when the staff become more proficient, more UCB units may be banked and the average cost to bank a UCB unit may be reduced.
According to previous reports, the discarded rate of UCB units was 25% to 69%.14,17-26 Different criteria for screening, study designs, and populations led to difficulties in making comparison for previous reports, and the most common reasons for deferral of potential donations were different in these studies. The most common exclusion reasons in the present study were low UCB weight (48.6%) and low cell count (30.9%). At the time during processing, we used 90 g and 6 × 108 cells as the criteria for storage, thereby setting strict criteria of UCB weight and/or volume and cell dose for banking UCB that resulted in a higher discard rate. For the best cost–benefit effect, clear and strict criteria to select appropriate UCB units are required for clinical purpose. The UCB volume is highly correlated to the TNC count, but automated cell counting is not available in some collection sites. We think that UCB unit volume may then be considered as an initial criterion for enrollment to reduce unnecessary expenditure in processing UCB units that do not meet sufficient cell dose.
McCullough and colleagues reported that the most common reason for UCB exclusion is donation denial (e.g., no scheduled collections on Saturday or Sunday and no scheduled collections from 11 p.m. to 7 a.m. on Monday to Friday), which comprised 5448 donations (45% of all excluded reasons). In our study, only 1.1 and 0.8% of the discarded UCB units were due to transportation and holiday reasons, which may be related to no collection restrictions on most holidays and the relatively small geographic area of Taiwan. Holidays and bad weather were usually the major problems for transport that caused exceeding of the maximum time limit (48 hr from harvesting to processing), but both could be improved as were observed in our analysis. Nevertheless, transportation and weather conditions must be considered for appropriate arrangement in advance to minimize collection of unsuitable UCB units.
In the study by McCullough and Clay, 2063 potential donors (17%) were excluded before collection due to obstetric complications or a history of high-risk birth (48.4% of them), problems with retrieval and/or preparation of the placenta or cord (32.2%), history of hepatitis or exposure to HIV or HIV infection (16.1%), and a nonsingleton fetus (3.2%). In our study, maternal medical problems (39.5%), maternal obstetric problems (25.7%), and artificial errors (20.3%) were the first three common causes of exclusion among the 612 potential donors excluded at the time before collection. The percentage of artificial errors before collection was remarkably high at the beginning. We created a video for collection and processing of UCB donation and began training the medical staff, administrative staff, and volunteers at that time. Hence, this problem markedly decreased in the 3-year collection period. Obstetric techniques such as harvesting the UCB by experienced professionals, placing the baby on the mother's abdomen immediately after birth, clamping the cord at the adequate position (as close as possible to the neonate), and appropriate timing of clamping the cord (30-60 sec after birth) have been reported to increase the volume and TNCs of UCB units.[29, 30] Improvement of obstetric collection skill as staff gained experience accumulated year after year would also lead to a decrease in the rate of exclusion in the situations such as problems with infant, placenta, umbilical cord, or low UCB weight.
Kurtzberg and coworkers reported that 10 and 2% of collected UCB units (ex utero method) were excluded because of positive maternal ID screening results and microbial contamination. Microbial contamination comprised 3.1 and 0.9% of UCB units being discarded in the studies of Lasky and colleagues (in utero and ex utero) and Lecchi and colleagues (in utero), respectively. In our study, the microbial contamination rates in all collected UCB units (in utero method) decreased from 3.3% in 2004 to 2.0% in 2006, reflecting an improvement on the techniques of obstetric and laboratory personnel. In our study, positive ID screening comprised 0.12% of the reasons for the UCB deletion, which was lower than the amount discarded in previous studies.[19, 20, 22] After freezing, we discarded only 154 UCB units (2.5% on the total discarded UCB units) because of infants' health problems or new family problems as noted in the questionnaire for the infants at 6 months of age. It suggested a technical improvement on the processing procedure and an enthusiastic attitude of our donors.
Strategies to avoid exclusion of CB units after collection are necessary to economize expenses for banking of useful UCB units. Lack of medical information on the mother or family caused 15 banked UCB units to be discarded in our experience. Thorough history taking before donation must be completed before collection. Nine UCB units were excluded because of donations without informed consent in 2004, but such mistakes have not occurred since 2005. Thirty-three UCB units were discarded because mothers were not reachable 6 months after the collections. Requesting additional mailing or e-mail addresses or telephone numbers of donors for contact could alleviate this problem. Although the numbers of this type of exclusion were small, they were usually preventable.
Most of our donors (99.3%) of the stored UCB unit completed the questionnaire; this high prevalence of participation was similar to that for the Milan Cord Blood Bank (94.5%). They reported that among the 2315 donors there was one congenital urinary malformation, one protein C deficiency, one phenylketonuria, one mucoviscidosis, and one chromosomal abnormality (10q-) detected by routine follow-up 6 months after birth. In the study by Volpe and coworkers, none of the 393 banked UCB units was removed at the clinical check at the 6-month follow-ups. This difference may be related to different populations and different criteria of enrollment. In our study, glucose-6-phosphate dehydrogenase deficiency comprised 76.5% of exclusion for the infants' health problems. It is preventable by including screening of family history in the recruitment questionnaire. The predonation health screening questionnaire should include common genetic problems that are specific to a population.
UCB banking includes several steps: donor recruitment, training, consenting, donor screening, and donor testing, as well as UCB collection, testing, processing, cryopreservation, and long-term storage. Efficient performance is necessary to decrease the expenditure of a UCB bank. We stopped UCB collection in 2008 because we had met the estimated target number of UCB units for our population (approx. 12,000 units). We observed that the exclusion rates for several modifiable causes decreased significantly during the study period. Understanding for exclusion reasons of UCB units may improve the efficiency of future UCB banking programs.